The disclosed systems and methods relate to extradural pressure monitors for monitoring and storing values related to intracranial pressure. The disclosed devices can be implanted in a head of a patient for either short- or long-term monitoring. The transmission of stored or real-time data to an external device consists of a radio-frequency communication circuit in the device.
Intracranial pressure rises in the settings of a number of acute insults to the brain including trauma, stroke, swelling, hemorrhage, and hydrocephalus. Currently there does not exist a wireless device that measures intracranial pressures reliably and safely. Such a device would improve monitoring in the hospital setting and would furthermore enable intracranial pressure monitoring in the outpatient setting.
Existing intracranial pressure (“ICP”) monitoring devices have significant shortcomings which make them impractical for stable and accurate monitoring of intracranial pressure for the long term. Most designs involve either externalization of a fluid column or tunneling a wire connection to an external monitor. As such methods leave an open tract between the external environment and the brain, the likelihood of infection is high.
Additionally, existing ICP devices have significant technical shortcomings. For example, many ICP devices are centered around gauges having a capacitance that varies with pressure, which are measured or sensed by LC circuits having a resonance that varies with this capacitance change. This approach, however, typically suffers from a great deal of drift in the gage readings.
Some designs involve measuring volume changes in a fixed amount of a trapped fluid, which, lacking adequate temperature compensation, make the device's readings subject to both bodily and environmental temperature changes. Additionally, previous designs' methods of transmitting data have been insufficient, as they have been slow, noisy, and inconsistent.